Valve tappet



Nov. 7, 1939. J. H. HoERN 2,178.724

VALVE TAPPET Filed April 19, 1938 NVENTR ..75e/' Hoer,

A TTORNE Ys'.

Patented Nov. 7, 1939 PATENT FFIQE VALVE TAPPET Joseph H. Hoern,Birmingham, Mich., assigner to Eaton Manufacturing Company,

Cleveland,

Ohio, a corporation of @hic Appiication April i9,

7 Claims.

This invention relates to valve tappets for internal combustion enginesand particularly to a valve tappet of the so-called barrel type, theprincipal object being the provision of a highly efficient tappet ofthis general type that is extremely economical to manufacture.

Objects of the invention include the provision of a barrel type valvetappet of hollow construction, the interior surfaces of which arepermanently sealed against the escape of foreign matter therefrom; theprovision of a valve tappet as above described formed from a pluralityof independently formed parts; the provision of a hollow barrel typevalve tappet the exterior surface of which is hardened throughout themajor portion of its area, certain portions of the tappet being formedof hardenable steel and other portions of the tappet being formed of amaterial of essentially non-hardening characteristics but the outersurface of which has been carburized and subsequently heated andquenched to harden the same; the provision of a barrel ktype valvetappet including a relatively thin walled hollow central body portiontogether with opposite end portions welded thereto, the hollow centralbody portion comprising a piece of metal bent into cylindrical formationand welded together at the opposed edges thereof; and the provision of ahollow barrel type valve tappet having a hermetically sealed hollowinterior and including an end member having a blind threaded openingtherein threadably receiving an adjusting means.

The above being among the objects of the present invention, the sameconsistsin certain novel features of construction and combinations ofparts to be hereinafter described with reference to the accompanyingdrawing, and then claimed, having the above and other objects in view.

In the accompanying drawing which illustrates a suitable embodiment ofthe present invention and in which like numerals refer to like partsthroughout the several different views,

Fig. 1 is a vertical sectional view taken axially through a valve tappetconstructed in accordance with the present invention;

Fig. 2 is a horizontal sectional view taken transversely through thevalve tappet shown in Fig. l as ony the line i2-2 thereof;

Fig. 3 is an exploded View in side elevation of the various componentparts going to make up the valve tappet shown in the previous views.

One disadvantage of barrel type valve tappets as heretofore constructedis that foreign material is inevitably found in the interior of thetappet and is liable to work out of it in service to the bearing surfacebetween the tappet and its guiding bore and to various other bearingsurfaces in internal combustion engines of which it forms a part, thusfostering the early destruction of such bearing surfaces. Such foreignmaterial 1938, Serial No. 202,928

(Cl. 12S-90) may occur in the nature of chips, shavings or the like ofthe material from which the tappet is made resulting from a machining orother step in the manufacture of the tappet, it may occur as a result ofcores or the like where the tappet is of cast construction, it may occuras scale Where the tappet is of a type requiring a hardening operationduring manufacture, it may occur as rust resulting from an intendedcleaning operation on the tappet by aqueous solutions, or for a numberof other different reasons. The present invention provides a tappet ofthis type which obviates the above disadvantage in that the hollowinterior of the tappet is hermetically sealed at an early stage in itsmanufacture thus eliminating the possibility of any foreign materialfinding its way into the interior 0f the tappet and positivelypreventing the escape of any foreign material from the interior of thetappet in service.

En the quantity production of valve tappets by more or less specializedmachinery, the ultimate cost of producing the tappets, as is true inconnection with a great many other articles produced in quantity,depends to a large extent upon the cost of material going into thetappet rather than to the cost of the various steps of operationthereon. Accordingly, in valve tappets which are to be produced in largequantities it is desirable to construct them of the cheapest materialpossible consistent with the ability to obtain the desiredcharacteristics in the nished product. With this end in view the presentinvention provides a construction by means of which certain portions ofthe tappet may be formed of the cheapest types of material, yet thenished product will have all of the desirable characteristics ofequivalent types of valve tappets heretofore produced from moreexpensive materials and will have certain definite advantages inaddition thereto. This is obtained in part by forming a part of thetappet from a relatively cheap grade of sheet metal and another part ofthe tappet from a relatively cheap grade of bar stock, these parts, inaccordance with a more limited phase of the invention, being carburizedduring manufacture so that in a subsequent hardening step to which theentire tappet is subjected the surfaces will be hardened to a desireddegree and yet the interior portions thereof will remain relatively softso as to enable the tappet to withstand impact without breakage and willpermit machining of certain parts thereof by the usual methods practicedon unhardened material after the tappets have passed through thehardening operation. In a broader aspect of the invention such parts,however, may be formed or" a so-called medium carbon steel that willbehardened to a greater or lesser extent upon heating and quenching.

Referring now to the drawing an illustrative embodiment of the tappetformed in accordance with the present invention is shown. This tappetcomprises a cylindrical main body portion i0. While in the broaderaspects of the invention the main body portion I0 may be formed fromseamless steel tubing or even machined out from the solid in accordancewith a more restricted phase of the invention, it is preferably formedfrom sheet metal bent into cylindrical shape and having its abuttingedges welded as at I2 in Fig. 2. In constructing the main body portionI0 from welded sheet metal as described, strips of sheet metal ofsuitable width may be formed into elongated tubes with the oppositeedges of the strip brought into abutting relation and welded together inaccordance with certain conventional methods of forming steel tubes,pipes or the like, and then sections of the desired length cut off. Onthe other hand a rectangular piece of sheet metal of the dimensionsrequired to make a hollow tube of the dimensions of the main bodyportion I0 may be simply rolled up to bring the opposite edges intoabutting relationship and then welding said edges together. Intermediateits length the portion I0 is preferably provided with one or moreperipheral grooves II adapted to retain a body of lubricant thereinduring operation.

One end of the main body portion I0 is provided with an end memberindicated generally at Ill and comprising a cylindrical body portion I6of a diameter materially less than the inner diameter of the main bodyportion I0 and a radially outwardly projecting central flange portion i0intermediate the ends thereof. The flange portion I8 is of an outerdiameter equal to the outer diameter of the main body portion I0 and iswelded thereto as at I9, preferably by a suitable resistance weldingoperation. The main body portion It of the end member I4 is providedwith a central threaded bore 2D extending axially inwardly thereof fromthe outer end and terminating short of the inner end of the main bodyportion IE so as to constitute a blind threaded opening for reception ofa clearance adjusting screw 22. That portion of the main body portion I6 outwardly of the flange I8 is iiattened olf on diametrically oppositeIsides to provide wrench receiving faces. The main body portion I5 ismade of a minimum diameter consistent with proper support of theadjusting screw to be received in the opening 20, its inwardlyprojecting end thus being radially spaced from the inner walls of themain body portion I0. From this it will be understood that if the hole20 were extended into open communication with the hollow interior of thetappet it would make it impossible to drain out any liquid employed inan attempt to wash out the interior of the tappet because of the pocketthus formed by such radial spacing, and the retention of such liquidwould result in rusting of the interioi` walls of the tappet.

In the broader aspects of the present invention any suitable type ofadjusting screw 22 may be employed, but the type shown is that disclosedand claimed in United States Letters Patent No. 2,035,055 granted March24, 1936 to Harold I. Dyer and owned by the assignee of the presentinvention, it being of a self-locking type eliminating the necessity ofemploying a lock nut in connection therewith.

The opposite end of the main body portion i0 is closed by a disc-likeend member 24 providing a surface for contacting the usual valve liftingcam of an internal combustion engine as is well understood in the art.rlhe end lll is preferably of the same outer diameter as the main bodyportion I0 and is suitably welded thereto as at 5 25, preferably by aresistance type of weld.

It will be understood from the description thus far given that theltappet shown in the drawing is hollow, that the ends I4 and 24 in beingwelded to the main body portion I0 are hermetically sealed thereto attheir points of connection, and that the main body portion I0 and end 24are imperforate and that the only opening in the end I4 is a blindopening so that the hollow interior of the tappet is hermetically 15sealed. This prevents any possible escape of any foreign material suchas that previously described from the interior of the tappet to theinterior of a cooperating engine during service and thereby positivelyeliminates any ill effects 20 which would otherwise occur from suchescape.

The end member 24 which is adapted to bear against a valve operating camis formed from a material which as a whole will be hardened to adesirable extent upon being heated and 25 quenched. One steel which issuitable for this purpose and which is mentioned as illustrative of thegeneral class of material from which the end member 24 may be formed isthat known as SAE #52,100 having the following composition. 30

Per cent Carbon 0.95-1.10 Manganese O20-0.50 Phosphorus maximum-- 0.030

Sulphur do 0.035 35 Chromium L20-1.50

Balance principally iron This material when suitably hardened will havea Rockwell hardness of at least 55, C scale. 40 Another suitable type ofsteel for the end member 24 where the same is to be carburized is thatknown as SAE #3115 having the following composition.

Per cent r Carbon 0.10-0.20 4 Manganese 0.30-0.60 Phosphorus maximum0.040 Sulphur do 0.050 Nickel LGO-1.50 r Chromium 045-035 "o Balanceprincipally iron In the broader aspects of the invention, the main bodyportion I0 at least, and the end member I4 if desired, may be formed ofa medium 55 carbon steel that may be hardened by heating and quenchingto a desired hardness, for instance, equal to 40 Rockwell, Scale C. Asindicative of the types of steel which may be employed for the main bodyportion and end mem- 60 ber i4 in such case, the composition of SAEsteel No. 1035 is here set out as a matter of illustration of asatisfactory steel for this purpose.

Per cent Carbon OSO-0.40 Manganese U50-0.90 Phosphorus maXimum 0.045Sulphur do 0.055

Balance principally iron Where, as is preferable for the sake of cheapness, the main body portion I0 and end member I4 in accordance with amore limited phase of the present invention are formed from a type ofsteel 'that is not hardenable in and of itself by 75- Vheating andlquenching, they may be formed of a type of steel such, for instance, asthat known as SAE #1020 having the following composition.

. Per cent Carbon 0.15-0.25

Manganese (LSU-0.60 Phosphorus maximum 0.045 Sulphur do 0.055

Balance principally iron Where the parts i and i4 are formed of amaterial which is not hardenable in and of itself by simply heating andquenching, nevertheless the exterior surfaces thereof and particularlythose surfaces thereof exposed to a sliding action in the cooperatingtappet bore of an engine in operation are hardened. This is accomplishedby carburining the exterior surfaces of these parts, as by packing inbone black and heating in accordance with conventional practice, to suchan extent that after the ends i4 and 24 have been Welded to the mainbody portion I0 and the entire assembly is heated to a suitabletemperature and quenched, not only will the end member 24 be hardened tothe desired extent but in addition the surface of the main body portionI0 and end member I4, because of the added carbon absorbed by suchsurfaces during the carburization treatment, will also be hardened. Aswill be understood by those skilled in the art the degree to which thesurfaces of the members I0 and I4 may be hardened and the depth of thehardened skin or surface thereof will depend upon the particular type ofcarburizing treatment to which these parts are subjected and the lengthof time to which they are subjected to such treatment, as well as thetemperature to which the parts are heated prior to quenching. Preferablyin such case the surfaces of the members II! and I4 are carburized tosuch an extent that when the entire assembly is heated to thetemperature required to obtain the desired hardening of the end 24 uponsubsequent quenching, the resulting hardness of the surface of the mainbody portion I0 will be in the neighborhood of 40 Rockwell, C scale, orhigher. Moreover, where the end member 24 is formed of SAE #3150 steelor its equivalent, it likewise is carburized so that its working facewill be hardened when heated and quenched, preferably to a hardness ofat least 60 Rockwell, or better. The particular manner of manufacturingthe tappets herein shown to obtain the various features referred toforms no part of the present invention but constitutes the subject of myco-pending application for Letters Patent of the United States forimprovements in Method of making valve tappets, led April 27, 1938 andserially numbered 204,692. In any event, regardless of the method ofmanufacture it will be observed that the tappet comprising the presentinvention has a hardened exterior surface and that the inner portions ofthe main body I0 and end member I4 is of relatively soft or at leastunhardened nature which renders the tappet relatively resistant torupture under impact and desirable for that reason.

It' will be understood that the particular embodiment of the inventionillustrated and described is subject to various changes in d-etails ofconstruction without departing from the spirit of the invention asdefined in the appended claims.

What I claim is:

1. A valve tappet comprising a hollow cylindrical main body portion, anend member closing one end of said main body portion and Welded thereto,and a second end member received by the opposite end of said main bodyportion and Welded thereto, the last mentioned end member being ofrelatively hard character and of uniform hardness therethrough, thesurface areas of said main body portion and the first mentioned endmember being of relatively hard character and said main body portion andsaid first mentioned end member being of relatively soft characterexcept for said surfaces.

2. A hollow valve tappet comprising an imperforate hollow cylindricalmain body portion, an imperforate end member secured and sealed to enend of said main body portion and having a blind threaded openingtherein, a second imperforate end member secured and sealed to theopposite end of said main body portion, the last mentioned end membercomprising material of relatively hard characteristics and ofsubstantially uniform hardness therethrough, and said main body portionand the first mentioned end member having exposed outer surfaces ofrelatively hard character and inner portions of unhardened material.

3. A valve tappet comprising a sheet metal main body portion oppositeedges of which are Welded along the line extending longitudinally ofsaid main body portion, end members secured to opposite ends of saidmain body portion, one of said end members being formed of relativelyhard material of substantially uniform hardness throughout and the otherof said end members and the main body portion having a relatively hardouter surface and a relatively soft interior body.

4. A valve tappet comprising a hollow cylindrical sheet metal bodyportion having a longitudinally extending weld therein, end memberswelded to opposite ends of said main body portion, one of said endmembers being formed of relatively hard material of substantiallyuniform hardness therethrough, the other of said end members and saidmain body portion having a greater carbon content in the exposed surfaceareas thereof than in the remainder thereof, said carbon contentextending into said longitudinal weld, those portions only of said otherend member and said main body portion including said greater carboncontent being hardened.

5. A barrel type valve tappet comprising a hollow cylindrical body ofsubstantially uniform dameter and uniform wall thickness throughout itslength and the interior of which is hermetically sealed, one end of saidbody having a shouldered member of substantially the same externaldiameter as the cylindrical body adjacent the portion where it is weldedthereto, the outer and inner axial portions of said member being ofsubstantially reduced diameter, the outer of said axial portions havinga relatively hard peripheral surface and a relatively soft interior,said interior of said outer axial portion being provided with a threadedblind opening therein, an adjusting screw received in said opening, anda member of harder characteristics than said body and the firstmentioned member closing the opposite end of said body.

6. A barrel type valve tappet comprising a hollow cylindricalimperforate body portion of substantially uniform diameter and uniformwall thickness throughout its length, imperforate end walls ofsubstantially the same external diameter as the body portion, welded insealed relation to opposite ends of said body portion, one of said endwalls having a blind threaded opening thereshaped groove in one face'thereofy received by the opposite end of said body portion and Weldedthereto, said disc-like end member being of relatively hard characterand of uniform hardness therethrough, the outer surface areas of saidbody portion and said shouldered end member being of relatively hardcharacter and said body portion and said shouldered end member being ofrelatively soft character except for said surfaces.

JOSEPH H. HOERN.

